There have conventionally been demands to collect logs relating to operating conditions of an electric motor or operating conditions of an inverter device in order that soundness of a whole system may be confirmed in the inverter device for motor drive by grasping a driving condition of the motor and the like or in order that a running rate of the whole system may be improved by making a maintenance program from a load status and an operating time of the motor. In order that logs may be collected without stop of the inverter device, the use of an external storage device has been proposed as the destination to save. The external storage device may include universal serial bus (USB) memories which are hot-swappable.
In this case, log acquisition in the inverter device is not always carried out by a skilled user. Accordingly, a complicated operation should be avoided in log acquisition as much as possible.